Dewatering apparatus for pulp



Nov. 22, 1927. J. STEPHANSEN DEWATERING APPARATUS Fon PULP Filed May 4, 1926 ll/Ill Patented Nov. 22, 1927-.

PATENT OFFICE.

JULIUS STEPHAN'SEN, 0F DRAINMEN, NORWAY.

DEWATERING APPARATUS FOB PULP.

Application filed May 4, 1926, Serial No. 106,704, and in Norway April 4,1025.

It is known to take up pulp on an endless sieve by means of suction boxes or rotating suction drums. It is also known to construct large screening cylinders covered with a stationary screen, the different parts of which.

are alternately and at certain portions of the circumference subjected to suction, partly in order to increase the outputof the machine and partly in order to exercise such suction upon the deposited pulp layer that thesame is freed from'water.

These apparatus are complicated and costly, and moreover it has been diicult to obtain, by means thereof, a sufficiently strong cylinder, whichl may stand the relatively great stress to which the peripherie portions thereof are subjected by contacting pressure drums &c.

Drums are also known which are intended 2U to be used at great pressures and which possess deep slots or grooves which extend around the periphery of the drum and receive the water which is filtered through the screen. The said water is then removed from the slots by means ofa suction box arranged at the free end of the outer surface of the slot drums. This arrangement is objectionable in that the point of the drum periphery which is nearest to the externally arranged suction box is subjected to the most intensive suction action, which latter, of course, decreases With the distance from the suction box, as the suction only can propagate circumferentially -through the narrow slots, which in the'neigliboroughood of the section box become full of Water. This is objectionable, as the suction action rather should increase than decrease as the thickness of the mass layer increases, which it 'does as dis- 40 tance of the said layer from the suction box is increasing.

The object of the present invention is to provide a dewatering ap aratus by means of which the above named rawbacks are avoided. The invention resides essentiall Ntherein that the apparatus is so constructe that an even suction action' is obtained at the entire effective ysurface thereof.v

The annexed drawing shows iii section way of example one embodiment of a de- 50 watering apparat-us according to the invention.

In` the drawing 1 is the hollow suction drum, the interior of which is',p1aced under a vacuum. The periphery of the drum is '55 provided with apertures 7 which may be circular, as in an usual perforated plate, or oblong, asin a strainer plate, which apertures extend into the inside of`v the ydrum.

An endless felt or strainer sieve 6 passes 60 around the drum in a manner' knownper se. At those portions where the said felt or sieve does not cover the drum there is arranged a cap or cover plate -5, which lies closely to the cylinder, in such manner that no air can at that place enter into the interior of the drum through the perforations.

The action 'of the apparatus is as follows: The felt or sieve moves past the open back Water channel 2 and receives a thin deposit of pulp. The back water is collected and may be utilized for diluting purposes or the like. As the felt 6 moves along with the rou tating drum 1 the vacuum -in the drum exerts a suction action upon the pulp upon the felt. p" The water hereby drawn ofl' passesthrough the felt 6 and the apertures in the eriphery of the drum 1, into the inside t ereof, from where the Water is removed through the hollow stub shaft 3 or through openings .S0 .4 in the end wall ofthe drum, which openings are connected with a suitable vacuum pump (not shown). The deposited pulp layer passes then in the usual manner past ressure drums 8 and is at last removed from 85 the felt in known manner.

Having now particularly described and ascertained the nature-of my said invention j and in what manner the same is to be performed, I declare. that what I claim is: 1. In a pul Vdewatering apparatus, the tcombination o a pulp container,'a rotatable perforated drum forming one side wall of said container, an endless felt or sieve passingn through said container and partly around said drum, and means associated with said' drum to prevent passage of iluids through said perforations along that part of the pe- ;iphery of the drum not in Contact with said elt.

2.111 a pulp dewatering apparatus, the combination of a pulp container, a rotatable perforated drum forming one side Wall of saideontainer, an endless felt or sieve passing through said container and partly around said drum, and means associated with 10 said drum to prevent access into the interior thereof along that part of the periphery of the drum not in Contact With said felt, said means comprising an arcuate cap disposed about the outside of and closely fitting the 15 periphery of said drum.

In testimony whereof-I aflix my signature.

J ULUS STEPHANSEN. 

